I'd save for Mewtwo personally (since you got 2 ttars already)...205k is what's needed for Level 20 -> 39...(and 218 candies).
Once I have enough for 1 maxed, then I'd probably work on the rest of the team...(meaning, save 205k always, and 218+ rare candies...). I'd probably start spending my rare candies when I hit 300+.
It'll probably take a while to get a 90%+ Mewtwo though.